Volume 5, Issue 1 NOV 2015

IJRAET

DESIGN AND ANALYSIS OF FORM TOOL

1 BIKUMALLA SRUTHI, 2 M ANIL KUMAR

1 Pg Scholar, Department of MECH, MLR INSTITUTE OF TECHNOLOGY, Ranga Reddy, Telangana, India. 2 Assistant Professor, Department of MECH, MLR INSTITUTE OF TECHNOLOGY, Ranga Reddy, Telangana, India.

Abstract— A form tool is precision-ground into a pattern

that resembles the part to be formed. The form tool can

be used as a single operation and therefore eliminate

many other operations from the slides (front, rear and/or

vertical) and the turret, such as box tools. A form tool

turns one or more diameters while feeding into the work.

Before the use of form tools, diameters were turned by

multiple slide and turret operations, and thus took more

work to make the part.

In this Project we model a form tool using CATIA V5.

The advantages of form tools are (a) cycle time, (b) it

works as “POKA YOKA” (mistake proofing) (c)

maintains relation between operation (d) cost

optimization. This tool is designed based upon the

component drawing supplied by the customer, spindle

power and rpm of CNC machine on which this tool is

proposed. This tool is modeled by using a 3D modeling

software.

In this the design of form tool is carried out using CATIA

modeling software, analyzed using FEA software ansys

workbench.

Keywords— tool, single point cutting tool, designing ,

modeling , simulation, structural simulation, stress ,

strain, deformation

I INTRODUCTION

Designing a forming tool is one of vital factor of tool

engineering, which must be known by every design

engineer. Forming a tool means giving a particular and

useful shape with required dimensions to the part. The part

formed by forming operation is generally takes the shape

of the dir or punch. In the forming operation, the metal

flow is not uniform and localized to some extent,

depending upon the shape of the work piece. Bending

along a large radius in a straight line may also be referred

to as a forming operation. It is difficult to distinguish

between a bending and forming tools. Forming operation

may be simple and extremely complicated.

A form tool is precision-ground into a pattern that

resembles the part to be formed. The form tool can be used

as a single operation and therefore eliminate many other

operations from the slides (front, rear and/or vertical) and

the turret, such as box tools. A form tool turns one or more

diameters while feeding into the work. Before the use of

form tools, diameters were turned by multiple slide and

turret operations, and thus took more work to make the

part. For example, a form tool can turn many diameters

and in addition can also cut off the part in a single

operation and eliminate the need to index the turret. For

single-spindle machines, bypassing the need to index the

turret can dramatically increase hourly part production

rates. On long-running jobs it is common to use a roughing

tool on a different slide or turret station to remove the bulk

of the material to reduce wear on the form tool.

There are different types of form tools. Insert form tools

are the most common for short- to medium-range jobs (50

to 20,000 pcs). Circular form tools are usually for longer

jobs, since the tool wear can be ground off the tool tip

many times as the tool is rotated in its holder. There is also

a skiving tool that can be used for light finishing cuts.

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Form tools can be made of cobalt steel, carbide, or high-

speed steel. Carbide requires additional care because it is

very brittle and will chip if chatter occurs.

A drawback when using form tools is that the feed into the

work is usually slow, 0.0005" to 0.0012" per revolution

depending on the width of the tool. Wide form tools create

more heat and usually are problematic for chatter. Heat

and chatter reduces tool life. Also, form tools wider than

2.5 times the smaller diameter of the part being turned

have a greater risk of the part breaking off. When turning

longer lengths, a support from the turret can be used to

increase turning length from 2.5 times to 5 times the

smallest diameter of the part being turned, and this also

can help reduce chatter. Despite the drawbacks, the

elimination of extra operations often makes using form

tools the most efficient option.

THEORY OF FORM TOOL:

PURPOSE OF FORMING TOOLS:

A form tool is defined as a cutting tool having one or more

cutting edges with well defined profile or contour that is

reproduced as the desired form on the work piece surface.

Form tools utilized for turning applications are classified

according to type of cross section. The classification is

shown in the tree diagram of Figure

Design of Metal Shaping Tools:

Flat or blocked tools are further classified according to the

setting of tool with respect to the work piece, viz. radial-

fed tools and tangential-fed tools. Further, form tools are

also classified with respect to orientation of tools with

respect to the work piece axis

VARIOUS TYPES OF FORMING TOOLS:

Flat Form Tool:Straight and flat form tools have a square

or rectangular cross-section with the form being along the

side or end. These tools are similar in appearance to the

turning tools. These are usually set centrally so that they

will cut their contour which is identical to the desired

contoured of the work piece. A typical example of V-notch

tool is shown in Figure. This type of tool is suitable for

making deep straight-sided form grooves. The cutting is

restricted type due to the mixed chip flow. Because of the

existence of the good surface finish, this type of tool must

be operated at very low cutting speed.

Figure shows a typical flat form tool without rake angle. It

is necessary to compute x to be machined in the tool in

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order that the depth BC is correct profile. This distance x is

to be planned by a fly cutter or planning tool and is

measured normal to the clearance face. The amount of x is

less than actual depth of form AB produced on the work

piece because of the clearance angle α. From the geometry

of the figure x = AB cos(α)

Figure shows a flat form tool with rake angle. The wedge

angle is given by (90 – γ – α). Using geometry of the

figure, the depth x to be ground or machined can be

determined in the following manner:

Introduction of rake angle to facilitate cutting action

modifies the profile on the tool.

Design of Forming Tools:

Circular Form Tool:

The circular form tool is circular in shape. It has depth x or

projection of distance x produced all around the diameter

in the form of annular grooves. The outside diameter of

circular form tool is determined in accordance with the

height of profile to be turned. The graphical method is

recommended for this purpose. Circular form tool is shown

in Figure.

GRAPHICAL METHOD OF DETERMINING

PROFILE OF FORM TOOL:

STRESSES ACTING ON A FORM TOOL:

Types of stress to which tools are exposed:

The types of tool load sustained in a range of non-chip

forming manufacturing techniques, are shown in figure.

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The upper die of cutting tools is exposed to shock-like

compressive and bending loads. The cutting and the lateral

area is affected by wear strain as a result of friction

between the work piece and the tool. The bottom die is

exposed to pressure and is subjected to mainly sliding

friction (wear). The face of the upper die and the surface of

the lower die should have as high a friction co-efficient as

possible, whilst the lateral area of the upper die should

have a low friction co-efficient so that the sheet does not

move during the cutting operation.

The situation in deep drawing operations is similar. Here,

the upper die is exposed mainly to pressure and only to a

low level of bending load, the lower die is exposed mainly

to friction and to a lesser degree to pressure. As in the

cutting operation, care must be taken to ensure that the

sheet does not flow at the upper die area. The friction co-

efficient should therefore be as high as possible at the

rounding of the upper die but low at the rounding of the

drawing ring.

In forward extrusion operations, compressive and

temperature stresses occur at the upper die and

compressive, tensile, friction and thermal stresses at the

lower die. Thermal load also develops in cold extrusion

operations as a result of the inner friction during material

flow.

The situation in the case of reverse extrusion is similar,

although the upper die is additionally affected by bending

and friction stresses.

The types of stress listed, also occur in varying degrees in

other processes such as extrusion, forging, pressure

casting and shell casting. The high operating temperatures

are particularly liable to cause stresses which are generally

masked in forging operations by additional shock stress.

TOOL DAMAGE AND WEAR: Types of damage

The types of damage shown in Fig., occur as a result of the

types of stress previously described. These may render the

tool unfit for use and include:

- Wear

- Mechanical crack formation

- Thermal crack formation

- Plastic deformation.

CAUSES OF DAMAGE AND THEIR MECHANISMS

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Since wear is the most important type of damage, it makes

sense to investigate its causes in more detail.

There is no one material characteristic which provides a

conclusive indication in itself, as to the level of wear

resistance of that material. This is because in the vast

majority of cases, a number of causes interact and combine

to cause wear in the tribo-technical systems in industrial

practice,

These include:

- Adhesion

- Abrasion

- Surface break-up and

- Tribo-chemical reaction

Wear inhibiting coatings are frequently equated with hard

coatings. This may be true in the case of abrasive wear, in

which there is a correlation in many cases between surface

hardness and wear resistance. However, this does not

apply to other types of wear or to a combination of

stresses, since factors other than hardness, such as surface

design, toughness etc. are also important.

The most important wear mechanisms and means of

reducing wear, are therefore discussed briefly in the

following

Adhesive wear: Occurs when bonding forces in the area

of the atomic lattice take effect between two metallic

materials. The prerequisite for this is that the lattices of the

bodies concerned, are structurally similar and that they

approach one another until there is only a short distance

between them. Furthermore, the more the lattice structures

of the materials concerned differ; the lower is their

susceptibility to adhesive wear.

Abrasive wear: Occurs when the harder of the two bodies

involved in the wear process, has pronounced roughness

beaks, which tear particles of material from the surface of

the softer body. Materials which are resistant to abrasive

wear, have outstanding hardness in comparison with the

abrading material. When there is surface breakdown, the

crystal and the structural condition is damaged irreversibly

as a result of alternating stresses and which depend on the

duration and level of stress involved. Surface breakdown is

reduced when the strength of a material is high, whereas

stress peaks and notch effects result in an increase.

Tribo-chemical reactions: Occur when the wear

processes take place only in the outermost boundary layer

of the bodies involved. This boundary or interfacial layer

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can be formed by reactions between the material and the

surrounding medium. Consequently, the wear

characteristics of the base material itself have no influence

on this process. It is not possible to specify any particular

material behavior in order to avoid the tribo-chemical

reaction, since the formation and characteristics of the

outer boundary layer are determined to an equal degree by

the material and by the surrounding medium.

Consequently, the lubricant is the primary determining

factor. The various types of damage sustained by tools, are

illustrated in Fig by the example of a forging die. In 70 %

of all cases in which tools become unfit for use, wear is the

underlying cause. Mechanical cracking occurs in 25 % of

all cases.

In contrast, plastic deformation and thermal cracking very

rarely mark the end of tool life. These results cannot be

transferred directly to other forming operations but wear

will be the most common type of wear there too, since

shock and temperature stress are generally lower in these

operations than in forging.

BASE MATERIAL AND BOUNDARY LAYER:

Requirements to be met by forming tools:

Due to the types of stress listed, there are a number of

special requirements which must be met by the base

material and the boundary layer of tools. These are shown

in Fig. The focus in the following is on the requirements to

be met by the wear and strength characteristics.

Requirements to be met by the base material and the

subsurface layer:

Tool materials for extrusion tools

MODELING & ANALYSIS:

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BASIC CROSS SECTIONAL PROFILE OF FORM

TOOL

CREATING SHAFT

CREATING POCKET

CREATING POCKET TO CREATE COUNTER OF

A TOOL

CREATING SLOT

CHAMFERING

THICKNESS

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DRAFTING OF FORM TOOL

GENERATED DRAWING LINES

FINATE ELEMENT ANALYSIS:

Imported model from CATIA to the format of IGES

DEFINING THE MATERIAL PROPERTIES

HSS OR HIGH SPEED STEEL

Yield strength: 250MPa

Density: 7.7e-006 kg mm^-3

Bulk Modulus: 1.7803e+005

Shear Modulus: 91797

Poisson's Ratio: 0.28

SILICONIZED SILICON CARBIDE

Density: 3.1e-006 kg mm^-3

Bulk Modulus: 3.2917e+005

Shear Modulus: 1.5192e+005

Poisson's Ratio: 0.28

MESHING:

Meshing for FORM TOOL

The above image showing the meshed modal, Default solid

Brick element was used to mesh the components. The

shown mesh method was called Tetra Hydra Mesh.

Meshing is used to deconstruct complex problem into

number of small problems based on finite element method.

APPLYING LOADS:

Rotational velocity of FORM TOOL

Force acting on FORM TOOL

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Fixed Support of FORM TOOL

RESULTS AND DISCUSSIONS

Stress Distribution of SISIC MATERIAL

Figure shows the total stress distribution of FORM TOOL

when the load is applied onto the contact surface. It has

been observed that the maximum stress developed is

68.986MPA.

Stress Distribution of HSS MATERIAL

Figure shows the total stress distribution of FORM TOOL

when the load is applied onto the contact surface. It has

been observed that the maximum stress developed is

48.957MPA.

Equivalent Elastic Strain Distribution of SISIC

MATERIAL

Figure shows the equivalent elastic strain distribution of

form tool when the load is applied onto the contact surface.

It has been observed that the maximum strain developed is

0.00017681mm/mm.

Equivalent Elastic Strain Distribution of HSS

MATERIAL

Figure shows the equivalent elastic strain distribution of

form tool when the load is applied onto the contact surface.

It has been observed that the maximum strain developed is

0.00020846mm/mm.

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TOTAL DEFORMATION of SISIC MATERIAL

Figure 4.5 shows the total deformation of form tool when

the load is applied onto the contact surface. It has been

observed that the total deformation developed is

0.00064053mm.

TOTAL DEFORMATION of HSS MATERIAL

Figure shows the total deformation of form tool when the

load is applied onto the contact surface. It has been

observed that the total deformation developed is

0.00080489mm.

MODAL ANALYSYS

The element type and various material properties such as

young’s modulus, density and Poisson’s ratio are

mentioned, and they are as

Young’s modulus: 2.35e+005Mpa

Density: 7.7e-006 kg mm^-3

Poisson's Ratio: 0.28

MODAL ANALYSYS OF HSS MATERIAL:

First mode shape of FORM TOOL

Second mode shape of FORM TOOL

Third mode shape of FORM TOOL

Fourth mode shape of FORM TOOL

Fifth mode shape of FORM TOOL

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Sixth mode shape of FORM TOOL

Results:

Static analysis

Modal analysis

CONCLUSION:

In this project we modeled a form tool according to

customer drawing/ requirement using CATIA V5. The

form tool reduces the waste as errors due to operator

fatigue, interruptions and production planning. The form

tool mainly used to reduce the machining time and

analyzed and stresses are using FINITE ELEMENT

ANALYSIS with SISIC material as compared to High

Speed Steel material

The following conclusions are drawn from the present

work

1. The Von mises stresses of HIGH SPEED STEEL are

obtained in static analysis is 48.957MPA Mpa and

Von mises stresses of SISIC is 68.986MPA

2. The deformation in HIGH SPEED STEEL

is0.00080489mm in static analysis and deformation in

SiSiC is 0.00064053mm.

3. The Stain Distribution in HIGH SPEED STEEL is

0.00020846mm/mm and strain distribution in SiSiC

is 0.00017681mm/mm

4. The Eigen values (natural frequencies) of HIGH

SPEED STEEL are 1546.5mm and Eigen values of

SiSiC is 1478.9mm

From above stress, strain, total deformation we can

observe that both HSS and SiSiC materials gave accurate

results for form tool but according to cost HSS material is

best.

References

1. http://www.makeitfrom.com/material-

group/Aluminum-Alloy/

2. http://www.matweb.com/search/PropertySearch.aspx

3. http://accessengineeringlibrary.com/maps/strength-of-

materials

4. http://www.technologystudent.com/joints/matprop1.ht

m

5. http://www.engineershandbook.com/Materials/mecha

nical.htm

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IJRAET

6. http://www.technologystudent.com/joints/matprop1.ht

m

7. https://en.wikipedia.org/wiki/Cnc-formtool

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